/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;

/**
 *
 * @author TungNT60513
 */
public class RegisterProcessing extends HttpServlet {

    private final String xmlPath = "xml/Users.xml";
    private final String homePage = "homePage.jsp";
    private final String errorPage = "errorpage.jsp";

    /**
     * Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        try {
            String userName = request.getParameter("txtUsername");
            String password = request.getParameter("txtPassword");
            String userEmail = request.getParameter("txtEmail");

            String realPath = getServletContext().getRealPath("/");
            String filePath = realPath + xmlPath;

            Document doc = xmlutils.XMLUtils.parseDOM(filePath);

            XPathFactory xpf = XPathFactory.newInstance();
            XPath xp = xpf.newXPath();

            String exp = "//*[local-name()='Username' and text()= '" + userName + "']";
            Boolean result = (Boolean) xp.evaluate(exp, doc, XPathConstants.BOOLEAN);

            if (!result) {
                Element user = doc.createElement("User");

                Element username = doc.createElement("Username");
                username.setTextContent(userName.trim());
                user.appendChild(username);

                Element pass = doc.createElement("Password");
                pass.setTextContent(password);
                user.appendChild(pass);

                Element email = doc.createElement("Email");
                email.setTextContent(userEmail);
                user.appendChild(email);

                Element isAdmin = doc.createElement("isAdmin");
                isAdmin.setTextContent("false");
                user.appendChild(isAdmin);

                NodeList listUsers = doc.getElementsByTagName("Users");
                listUsers.item(0).appendChild(user);

                xmlutils.XMLUtils.writeXML(doc, filePath); // ghi node vao file xml
                RequestDispatcher rd = request.getRequestDispatcher(homePage);
                rd.forward(request, response);
            } else {
                request.getSession(true).setAttribute("message", "Tên đăng nhập đã tồn tại!");
                RequestDispatcher rd = request.getRequestDispatcher(errorPage);
                rd.forward(request, response);
            }



        } catch (XPathExpressionException ex) {
            Logger.getLogger(RegisterProcessing.class.getName()).log(Level.SEVERE, null, ex);
        } finally {
            out.close();
        }
    }

    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /** 
     * Handles the HTTP <code>GET</code> method.
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /** 
     * Handles the HTTP <code>POST</code> method.
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /** 
     * Returns a short description of the servlet.
     * @return a String containing servlet description
     */
    @Override
    public String getServletInfo() {
        return "Short description";
    }// </editor-fold>
}
